Image sensor and electronic device including the same

ABSTRACT

An image sensor includes a semiconductor substrate integrated with at least one first photo-sensing device configured to sense light in a blue wavelength region and at least one second photo-sensing device configured to sense light in a red wavelength region, a color filter layer on the semiconductor substrate and including a blue color filter configured to selectively absorb light in a blue wavelength region and a red color filter configured to selectively absorb light in a red wavelength region, and a third photo-sensing device on the color filter layer and including a pair of electrodes facing each other, and a photoactive layer between the pair of electrodes and configured to selectively absorb light in a green wavelength region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/143,909, filed on May 2, 2016, which is a continuation of U.S.application Ser. No. 14/560,920, filed on Dec. 4, 2014, which claimspriority under 35 U.S.C. §119 to the benefit of Korean PatentApplication No. 10-2014-0005310 filed in the Korean IntellectualProperty Office on Jan. 15, 2014, and Korean Patent Application No.10-2014-0098567 filed in the Korean Intellectual Property Office on Jul.31, 2014, the entire contents of each of which are incorporated hereinby reference.

BACKGROUND 1. Field

Example embodiments are directed to an image sensor and an electronicdevice including the same.

2. Description of the Related Art

A photoelectric device converts light into an electrical signal usingphotoelectric effects, and may include a photodiode and/or aphototransistor, and may be applied to an image sensor and/or a solarcell.

An image sensor including a photodiode requires relatively highresolution and thus a relatively small pixel. However, at present, asilicon photodiode is widely used, but it may have a problem ofdeteriorated sensitivity because the silicon photodiode has a relativelysmall absorption area due to relatively small pixels.

SUMMARY

Example embodiments provide an image sensor that is desirable for beingdown-sized and is capable of decreasing sensitivity deterioration whilehaving a high resolution.

Example embodiments also provide an electronic device including theimage sensor.

According to example embodiments, an image sensor includes asemiconductor substrate integrated with at least one first photo-sensingdevice configured to sense light in a blue wavelength region and atleast one second photo-sensing device configured to sense light in a redwavelength region, a color filter layer on the semiconductor substrateand including a blue color filter configured to selectively absorb lightin a blue wavelength region and a red color filter configured toselectively absorb light in a red wavelength region, and a thirdphoto-sensing device on the color filter layer and including a pair ofelectrodes facing each other, and a photoactive layer between the pairof electrodes and configured to selectively absorb light in a greenwavelength region.

The blue wavelength region may have a maximum absorption wavelength(λ_(max)) in a region of greater than or equal to about 400 nm and lessthan about 500 nm, the red wavelength region may have a maximumabsorption wavelength (λ_(max)) in a region of greater than about 580 nmand less than or equal to about 700 nm, and the green wavelength regionmay have a maximum absorption wavelength (λ_(max)) in a region of about500 nm to about 580 nm.

The pair of electrodes may be light-transmitting electrodes, and thephotoactive layer includes a p-type semiconductor material and an n-typesemiconductor material, at least one of the p-type semiconductormaterial and the n-type semiconductor material configured to selectivelyabsorb light in the green wavelength region.

The image sensor may further include a focusing lens on the thirdphoto-sensing device.

The image sensor may further include a metal wire beneath the at leastone first photo-sensing device and the at least one second photo-sensingdevice.

The image sensor may further include a semi-transmitting layer betweenthe third photo-sensing device and the color filter layer.

The semi-transmitting layer may be configured to transmit light in theblue wavelength region and the red wavelength region and may beconfigured to selectively reflect light in the green wavelength region.

The semi-transmitting layer may include a plurality of first and secondlayers alternately stacked on the semiconductor substrate, the pluralityof first layers having different refractive indices from the pluralityof second layers.

The thickness of each of the plurality of first and second layers may bedetermined by the refractive indices and reflective wavelengths of theplurality of first and second layers.

A full width at half maximum of the green wavelength region in alight-absorption spectrum may be determined by a ratio of the refractiveindices of the plurality of first and second layers.

The plurality of first layers may have the refractive index of about 1.2to about 1.8, and the plurality of second layers may have the refractiveindex of about 2.1 to about 2.7.

Each of the plurality of first layers may be a silicon oxide layer, andeach of the plurality of second layers may be a titanium oxide layer.The semi-transmitting layer may include a plurality of silicon oxidelayers and a plurality of titanium oxide layers alternately stacked onthe semiconductor substrate to form 5 to 10 layers, and each of theplurality of silicon oxide layers may have a thickness of about 10 nm to300 nm, and each of the plurality of titanium oxide layers has athickness of about 30 nm to 200 nm.

According to example embodiments, an electronic device includes theimage sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments,

FIG. 2 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments,

FIG. 3 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments,

FIG. 4 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments,

FIG. 5 is a cross-sectional view showing a semi-transmitting layer inthe image sensor of FIG. 4,

FIG. 6 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments, and

FIG. 7 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments.

DETAILED DESCRIPTION

Example embodiments will hereinafter be described in detail, and may beeasily performed by those who have common knowledge in the related art.However, this disclosure may be embodied in many different forms and isnot construed as limited to the example embodiments set forth herein.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

Referring to drawings, an image sensor according to example embodimentsis described. Herein, a CMOS image sensor as an example of an imagesensor is described.

FIG. 1 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments.

An image sensor according to example embodiments includes a first pixel,a second pixel, and a third pixel that are adjacent to one another. Thefirst pixel, second pixel, and third pixel may have different absorptionwavelength regions in a visible ray region, for example, about 380 to780 nm, and for example the first pixel may be a blue pixel sensinglight in a blue wavelength region, the second pixel may be a red pixelsensing light in a red wavelength region, and the third pixel may be agreen pixel sensing light in a green wavelength region.

The blue wavelength region may have a maximum absorption wavelength(λ_(max)) in a region of greater than or equal to about 400 nm and lessthan about 500 nm, the red wavelength region may have a maximumabsorption wavelength (λ_(max)) in a region of greater than about 580 nmand less than or equal to about 700 nm, and the green wavelength regionmay have a maximum absorption wavelength (λ_(max)) in a region of about500 nm to about 580 nm.

The blue, red, and green pixels may be repeatedly arranged as one groupalong a row and/or column. However, the pixel disposition may bevariously modified.

Referring to FIG. 1, an image sensor 300 according to exampleembodiments includes a semiconductor substrate 310 integrated with ablue photo-sensing device 50B, a red photo-sensing device 50R, a chargestorage device 50G, and a transmission transistor (not shown), a lowerinsulation layer 60, a color filter layer 70, an upper insulation layer80, and a green photo-sensing device 100.

In FIG. 1, a constituent element including “B” in the reference symbolrefers to a constituent element included in the blue pixel, aconstituent element including “R” in the reference symbol refers to aconstituent element included in the red pixel, and a constituent elementincluding “G” in the reference symbol refers to a constituent elementincluded in the green pixel.

The semiconductor substrate 310 may be a silicon substrate, and the bluephoto-sensing device 50B, the red photo-sensing device 50R, the chargestorage device 50G, and transmission transistor (not shown) areintegrated therein. The blue photo-sensing device 50B and redphoto-sensing device 50R may be photodiodes. The blue photo-sensingdevice 50B and the transmission transistor may be integrated in eachblue pixel, the red photo-sensing device 50R and the transmissiontransistor may be integrated in each red pixel, and the charge storagedevice 50G and the transmission transistor may be integrated in eachgreen pixel.

Metal wires (not shown) and pads (not shown) are formed on thesemiconductor substrate 310. In order to decrease signal delay, themetal wires and pads may be made of a metal having relatively lowresistivity, for example, aluminum (Al), copper (Cu), silver (Ag), andalloys thereof, but are not limited thereto.

The lower insulation layer 60 may be formed on the metal wire and pad.The lower insulation layer 60 may be, for example, made of an inorganicinsulation material (e.g., a silicon oxide and/or a silicon nitride), ora low dielectric constant (low K) material (e.g., SiC, SiCOH, SiCO, andSiOF).

The lower insulation layer 60 may have trenches (not shown) exposingphoto-sensing devices 50B and 50R and the charge storage device 50G ofeach pixel. The trench may be filed with a filler.

The color filter layer 70 is formed on the lower insulation layer 60.The color filter layer 70 includes a blue color filter 70B of a bluepixel and a red color filter 70R of a red pixel. The blue color filter70B may absorb light in a blue wavelength region and transmits it to theblue photo-sensing device 50B, and the red color filter 70R may absorblight in a red wavelength region and transmits it to the redphoto-sensing device 50R. The green pixel does not include a colorfilter.

The upper insulation layer 80 is formed on the color filter layer 70.The upper insulation layer 80 may reduce the steps necessary due to thecolor filter layer 70, and make it be planarized. The upper insulationlayer 80 and lower insulation layer 60 have a contact hole (not shown)exposing the pad, and a through-hole 85 exposing the charge storagedevice 50G of the green pixel.

The green photo-sensing device 100 is formed on the upper insulationlayer 80. The green photo-sensing device 100 includes a lower electrode110 and an upper electrode 120 facing each other, and a photoactivelayer 130G interposed between the lower electrode 110 and the upperelectrode 120. One of the lower electrode 110 and the upper electrode120 is an anode and the other is a cathode.

The lower electrode 110 and the upper electrode 120 may belight-transmitting electrodes, and the light-transmitting electrodes maybe made of, for example, a transparent conductor (e.g., indium tin oxide(ITO) or indium zinc oxide (IZO)), or may be a metal thin layer having arelatively thin thickness of several nanometers or several tens ofnanometers or a metal thin layer having a relatively thin thickness ofseveral nanometers to several tens of nanometers doped with a metaloxide.

The photoactive layer 130G may selectively absorb light in a greenwavelength region, and transmit light in other wavelength region besidesthe green wavelength region, that is, light in a blue wavelength regionand a red wavelength region.

The photoactive layer 130G may include a p-type semiconductor materialand an n-type semiconductor material, and the p-type semiconductormaterial and the n-type semiconductor material may form a pn junction.At least one of the p-type material and the n-type material mayselectively absorb light in a green wavelength region, and for examplethe p-type material and the n-type material may selectively absorb lightin a green wavelength region. The photoactive layer 130G may selectivelyabsorb light in a green wavelength region to generate excitons, and thenthe generated excitons may be separated into holes and electrons toprovide a photoelectric effect. The photoactive layer 130G may replace acolor filter of a green pixel.

Each of the p-type semiconductor material and the n-type semiconductormaterial may have an energy bandgap of, for example, about 2.0 to about2.5 eV, and the p-type semiconductor material and the n-typesemiconductor material may have a LUMO difference of, for example, about0.2 to about 0.7 eV.

The p-type semiconductor material may be, for example, quinacridone or aderivative thereof, and the n-type semiconductor material may be, forexample, a cyanovinyl group-containing thiophene derivative, but theyare not limited thereto.

The quinacridone or derivative thereof may be, for example, representedby the following Chemical Formula 1.

In the Chemical Formula 1,

each of R¹ and R² are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₆to C₃₀ aryl group, a substituted or unsubstituted C₃ to C₃₀ heteroarylgroup, and a combination thereof,

each of X¹ and X² are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₂to C₃₀ alkenyl group, a substituted or unsubstituted C₆ to C₃₀ aromaticgroup, a substituted or unsubstituted C₃ to C₃₀ heterocyclic aromaticgroup, a cyano-containing group, a halogen-containing group, and acombination thereof.

The quinacridone or derivatives thereof may be represented by, forexample, the following Chemical Formulae 1a to 1o, but are not limitedthereto.

In the Chemical Formulae 1a to 1o, R¹ and R² are the same as describedabove.

The thiophene derivative may be represented by, for example, thefollowing Chemical Formula 2.

In the Chemical Formula 2,

each of T¹, T², and T³ are independently an aromatic ring having asubstituted or unsubstituted thiophene moiety, and

each of X³ to X⁸ are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₆to C₃₀ aryl group, a substituted or unsubstituted C₃ or C₃₀ heteroarylgroup, a cyano group, and a combination thereof. At least one of X³ toX⁸ may be a cyano group.

The T¹, T², and T³ may be independently selected from groups listed inthe following Group 1.

[Group 1]

In the Group 1,

each of R¹¹ to R²⁶ are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₆to C₃₀ aryl group, a substituted or unsubstituted C₃ to C₃₀ heteroarylgroup, and a combination thereof.

The thiophene derivative may be, for example, selected from a compoundrepresented by the following Chemical Formulae 2a to 2j, but is notlimited thereto.

In the above Chemical Formulae 2h or 2j,

each of X₁ to X₅ are the same or different and are independently one ofCR¹R², SiR³R⁴, NR⁵, oxygen (O), and selenium (Se), wherein each of R¹ toR⁵ are the same or different and are independently one of hydrogen, asubstituted or unsubstituted C1 to C20 alkyl group, a substituted orunsubstituted C6 to C20 aryl group, a substituted or unsubstituted C3 toC20 heteroaryl group, and a combination thereof.

The p-type semiconductor material may be, for example a compoundrepresented by the Chemical Formula 3, and the n-type semiconductormaterial may be, for example, a compound represented by the ChemicalFormula 4, but they are not limited thereto.

In the Chemical Formula 3,

each of R¹ to R⁸ are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₆to C₃₀ aryl group, a substituted or unsubstituted C₃ to C₃₀ heteroarylgroup, a substituted or unsubstituted C₁ to C₃₀ alkoxy group, a halogenatom, a halogen-containing group, and a combination thereof,

wherein two adjacent groups of R¹ to R⁸ may be bonded together to form aring or a fused ring, and

at least one of R¹ to R⁸ is one of a substituted or unsubstituted C₆ toC₃₀ aryl group, a substituted or unsubstituted C₃ to C₃₀ heteroarylgroup, and a combination thereof.

In the Chemical Formula 4,

each of Z¹ to Z⁴ are independently one of oxygen (O), nitrogen (N), andsulfur (S),

each of X^(a1) to X^(a5), X^(b1) to X^(b5), X^(c1) to X^(c5), and X^(d1)to X^(d5) are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₆to C₃₀ aryl group, a halogen atom, a halogen-containing group, and acombination thereof, and

each of X⁵ and X⁶ are independently one of hydrogen, a substituted orunsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstituted C₆to C₃₀ aryl group, a substituted or unsubstituted C₃ to C₃₀ heteroarylgroup, and a combination thereof.

The compound represented by the Chemical Formula 3 may be, for example,a compound represented by one of the Chemical Formulae 3a to 3d, and thecompound represented by the Chemical Formula 4 may be, for example, acompound represented by the Chemical Formula 4a or 4b, but they are notlimited thereto.

The p-type semiconductor material may be, for example, the abovequinacridone or derivatives thereof, and the n-type semiconductormaterial may be, for example, a compound represented by the followingChemical Formula 5, but they are not limited thereto.

In the Chemical Formula 5,

each of R^(a) to R^(l) are independently one of hydrogen, a substitutedor unsubstituted C₁ to C₃₀ alkyl group, a substituted or unsubstitutedC₆ to C₃₀ aryl group, a substituted or unsubstituted C₃ to C₃₀heteroaryl group, a halogen atom, a halogen-containing group, and acombination thereof, and

X is one of a halogen atom and a C₆ to C₂₀ aryloxy group including atleast one halogen atom.

The compound represented by the Chemical Formula 5 may be, for exampleat least one of compounds represented by the following Chemical Formulae5a to 5g, but is not limited thereto.

The photoactive layer 130G may be a single layer or a multilayer. Thephotoactive layer 130G may be, for example, an intrinsic layer (Ilayer), a p-type layer/I layer, an I layer/n-type layer, a p-typelayer/I layer/n-type layer, and/or a p-type layer/n-type layer.

The intrinsic layer (I layer) may include the p-type semiconductormaterial and the n-type semiconductor material in a thickness ratio ofabout 1:100 to about 100:1. The materials may be included in a thicknessratio ranging from about 1:50 to about 50:1 within the range, forexample, about 1:10 to about 10:1, or about 1 to about 1. When thep-type and n-type semiconductor materials have a composition ratiowithin the range, an exciton may be effectively produced, and a pnjunction may be effectively formed.

The p-type layer may include the p-type semiconductor material, and then-type layer may include the n-type semiconductor material.

The photoactive layer 130G may have a thickness of about 1 nm to about500 nm. Within the range, the photoactive layer 130G may have athickness of about 5 nm to about 300 nm. When the photoactive layer 130Ghas a thickness within the range, the photoactive layer may effectivelyabsorb light, effectively separate holes from electrons, and deliverthem, effectively improving photoelectric conversion efficiency.

In the green photo-sensing device 100, when light is incident from theupper electrode 120 and then the photoactive layer 130G absorbs light ina green wavelength region, excitons may be produced from the inside. Theexcitons are separated into holes and electrons in the photoactive layer130G, and the separated holes are transported to an anode that is one ofthe lower electrode 110 and the upper electrode 120, and the separatedelectrons are transported to the cathode that is the other of the lowerelectrode 110 and the upper electrode 120 so as to flow a current. Theseparated electrons or holes may be gathered in the charge storagedevice 50G. Light in other wavelength regions except for a greenwavelength region pass the lower electrode 110 and color filters 70B and70G and may be sensed by the blue photo-sensing device 50B or the redphoto-sensing device 50R.

The photoactive layer 130G may be formed on the front of the imagesensor 300 and absorb light thereon, and thus increase a photo area andbring about high absorption efficiency.

On the green photo-sensing device 100, a focusing lens (not shown) maybe further formed. The focusing lens may control direction of incidentlight and gather the light in one region. The focusing lens may have ashape of, for example, a cylinder or a hemisphere, but is not limitedthereto.

In this way, a color filter layer including a color filter absorbinglight in blue and red wavelength regions in visible rays and a greenphoto-sensing device absorbing light in a green wavelength region arevertically stacked, and thus may decrease an area of an image sensor anddown-size the image sensor.

In addition, a photo-sensing device selectively absorbing light in agreen wavelength region is formed on the front of the image sensor, andthus may increase its area absorbing light and secure an area of thecolor filter layer and increase absorption efficiency.

FIG. 2 is a cross-sectional view showing an organic photoelectronicdevice according to example embodiments.

Referring to FIG. 2, a CMOS image sensor 200 according to exampleembodiments includes a semiconductor substrate 310 integrated with ablue photo-sensing device 50B, a red photo-sensing device 50R, a chargestorage device 50G, and a transmission transistor (not shown), a lowerinsulation layer 60, a color filter layer 70, an upper insulation layer80, and a green photo-sensing device 100, like example embodiments asillustrated in FIG. 1.

The color filter layer 70 includes a blue color filter 70B of a bluepixel and a red color filter 70R of a red pixel, and the greenphoto-sensing device 100 includes a lower electrode 110, a photoactivelayer 130G, and an upper electrode 120. The photoactive layer 130G mayselectively absorb light in a green wavelength region and transmit lightin other wavelength region besides the green wavelength region, that is,light in a blue wavelength region and a red wavelength region, asdescribed above.

However, a metal wire 320 is positioned beneath the blue photo-sensingdevice 50B, the red photo-sensing device 50R, and the charge storagedevice 50G, unlike the example embodiments illustrated in FIG. 1. Whenthe metal wire 320 is positioned beneath the blue photo-sensing device50B, the red photo-sensing device 50R, and the charge storage device50G, light loss due to reflection of the metal wire 320 made of anopaque metal decreases, light efficiency increases, and lightinterference among pixels may be effectively reduced.

FIG. 3 is a cross-sectional view showing an organic photoelectronicdevice according to example embodiments.

Referring to FIG. 3, a CMOS image sensor 300 according to exampleembodiments includes a semiconductor substrate 310 integrated with ablue photo-sensing device 50B, a red photo-sensing device 50R, a chargestorage device 50G, and a transmission transistor (not shown), a lowerinsulation layer 60, a color filter layer 70, an upper insulation layer80, and a green photo-sensing device 100, like the example embodimentsillustrated in FIG. 2.

The color filter layer 70 includes a blue color filter 70B of a bluepixel and a red color filter 70R of a red pixel, and the greenphoto-sensing device 100 includes a lower electrode 110, a photoactivelayer 130G, and an upper electrode 120. The photoactive layer 130G mayselectively absorb light in a green wavelength region and transmit lightin other wavelength region besides the green wavelength region, that is,light in a blue wavelength region and a red wavelength region, asdescribed above.

However, the green photo-sensing device 100 further includes chargeauxiliary layers 140 and 150 between the lower electrode 110 and thephotoactive layer 130G and between the upper electrode 120 and thephotoactive layer 130G, unlike the example embodiments illustrated inFIG. 2. Either one of the charge auxiliary layers 140 and 150 may beomitted.

The charge auxiliary layers 140 and 150 may be at least one selectedfrom a hole injection layer (HIL) for facilitating hole injection, ahole transport layer (HTL) for facilitating hole transport, an electronblocking layer (EBL) for preventing or inhibiting electron transport, anelectron injection layer (EIL) for facilitating electron injection, anelectron transport layer (ETL) for facilitating electron transport, anda hole blocking layer (HBL) for preventing or inhibiting hole transport.

The charge auxiliary layers 140 and 150 may include, for example, anorganic material, an inorganic material, or an organic/inorganicmaterial. The organic material may include an organic compound havinghole or electron characteristics, and the inorganic material may be, forexample, a metal oxide (e.g., molybdenum oxide, tungsten oxide and/ornickel oxide).

The hole transport layer (HTL) may include one selected from, forexample, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS), polyarylamine, poly(N-vinylcarbazole), polyaniline,polypyrrole, N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (TPD),4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA,4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA), and a combinationthereof, but is not limited thereto. The electron blocking layer (EBL)may include one selected from, for example,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS),polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole,N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (TPD),4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA,4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA), and a combinationthereof, but is not limited thereto.

The electron transport layer (ETL) may include one selected from, forexample, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA),bathocuproine (BCP), LiF, Alq₃, Gaq₃, Inq₃, Znq₂, Zn(BTZ)₂, BeBq₂, and acombination thereof, but is not limited thereto.

The hole blocking layer (HBL) may include one selected from, for example1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine(BCP), LiF, Alq₃, Gaq₃, Inq₃, Znq₂, Zn(BTZ)₂, BeBq₂, and a combinationthereof, but is not limited thereto.

FIG. 4 is a cross-sectional view of an organic CMOS image sensoraccording to example embodiments.

The CMOS image sensor 400 according to example embodiments includes asemiconductor substrate 310 integrated with a blue photo-sensing device50B, a red photo-sensing device 50R, a charge storage device 50G, and atransmission transistor, a lower insulation layer 60, a color filterlayer 70, a upper insulation layer 80, and a green photo-sensing device100, like the example embodiments illustrated in FIG. 3.

The color filter layer 70 includes a blue color filter 70B of a bluepixel and a red color filter 70R of a red pixel, and the greenphoto-sensing device 100 includes a lower electrode 110, a photoactivelayer 130G, and an upper electrode 120. The photoactive layer 130G mayselectively absorb light in a green wavelength region, and transmitlight in other wavelength region besides the green wavelength region,that is, light in a blue wavelength region and a red wavelength region,as described above.

However, the organic photoelectronic device 300 according to exampleembodiments further include a semi-transmitting layer 90 between thegreen photo-sensing device 100 and the color filter layer 70, unlike theexample embodiments illustrated in FIG. 3.

The semi-transmitting layer 90 may transmit a part of light and reflecta part of light, and for example, selectively transmit light in the bluewavelength region and the red wavelength region and selectively reflectlight in the green wavelength region.

The semi-transmitting layer 90 may reflect light in the green wavelengthregion that is not absorbed in the photoactive layer 130G, to thephotoactive layer 130G again, and thus improves a light absorption ratein a green wavelength region of the photoactive layer 130G. Therefore,efficiency of the green photo-sensing device 100 may be improved.

The semi-transmitting layer 90 may have, for example, a distributedBragg reflection (DBR) structure.

FIG. 5 is a cross-sectional view showing an example of asemi-transmitting layer in the image sensor of FIG. 4.

Referring to FIG. 5, the semi-transmitting layer 90 may include aplurality of layers where a first layer 90 a and a second layer 90 bhaving a different refractive index from each other are alternatelystacked on the semiconductor substrate 310, and may include, forexample, 5 to 10 layers.

The first layer 90 a may be a low refractive index layer, and the secondlayer 90 b may be a high refractive index layer. For example, the firstlayer 90 a may have a refractive index of about 1.2 to about 1.8, andthe second layer 90 b may have a refractive index of about 2.1 to about2.7. Within the range, the first layer 90 a may have may have arefractive index of about 1.44 to about 1.47, and the second layer 90 bmay have a refractive index of about 2.31 to about 2.45. The first layer90 a and the second layer 90 b may include any material having therefractive index without particular limitation, and for example, thefirst layer may be a silicon oxide layer, and the second layer may be atitanium oxide layer. Within the ranges, a ratio of refractive indicesof the first layer and the second layer may be controlled easily inorder to increase selectivity for absorbing light in a green wavelength.

The thicknesses of the first layer 90 a and the second layer 90 b may bedetermined by each refractive index and reflective wavelength of eachlayer, and for example, each first layer 90 a may have a thickness ofabout 10 nm to about 300 nm, and each second layer 90 b may have athickness of about 30 nm to about 200 nm. The semi-transmitting layer 90may have a total thickness of, for example, about 770 nm to about 1540nm. The thicknesses of each first layer 90 a and each second layer 90 bmay be the same or different.

As a refractive index n₁ of the first layer 90 a and a refractive indexn₂ of the second layer 90 b have a larger difference from each other,the semi-transmitting layer 90 may have higher wavelength selectivity,and for example, a ratio between the refractive index n₁ of the firstlayer 90 a and the refractive index n₂ of the second layer 90 b maydetermine a full width at half maximum (FWHM) of the third wavelengthregion in a light-absorption spectrum. Herein, the full width at halfmaximum indicates width of a wavelength corresponding to a half of themaximum absorbance point, and thus a small full width at half maximumindicates selective absorption of light in a narrow wavelength regionand high wavelength selectivity. In other words, as the ratio betweenthe refractive index n₁ of the first layer 90 a and the refractive indexn₂ of the second layer 90 b, that is, a ratio of n₂/n₁, becomes larger,the full width at half maximum becomes narrower, increasing wavelengthselectivity.

FIG. 6 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments.

Referring to FIG. 6, a CMOS image sensor 500 according to exampleembodiments includes a semiconductor substrate 310 integrated with ablue photo-sensing device 50B, a red photo-sensing device 50R, a chargestorage device 50G, and a transmission transistor (not shown), a lowerinsulation layer 60, a color filter layer 70, a upper insulation layer80, a semi-transmitting layer 90, and a green photo-sensing device 100,like example embodiments as illustrated in FIG. 4.

The color filter layer 70 includes a blue color filter 70B of a bluepixel and a red color filter 70R of a red pixel, and the greenphoto-sensing device 100 includes a lower electrode 110, a photoactivelayer 130G, and an upper electrode 120. The photoactive layer 130G mayselectively absorb light in a green wavelength region and transmit lightin other wavelength region besides the green wavelength region, that is,light in a blue wavelength region and a red wavelength region, asdescribed above.

However, a metal wire 320 is positioned beneath the blue photo-sensingdevice 50B, the red photo-sensing device 50R, and the charge storagedevice 50G, unlike the example embodiments of FIG. 4. When the metalwire 320 is positioned beneath the blue photo-sensing device 50B, thered photo-sensing device 50R, and the charge storage device 50G, lightloss due to reflection of the metal wire 320 made of an opaque metaldecreases, light efficiency increases, and light interference amongpixels may be effectively reduced.

FIG. 7 is a cross-sectional view showing a CMOS image sensor accordingto example embodiments.

Referring to FIG. 7, a CMOS image sensor 600 according to exampleembodiments includes a semiconductor substrate 310 integrated with ablue photo-sensing device 50B, a red photo-sensing device 50R, a chargestorage device 50G, and a transmission transistor (not shown), a lowerinsulation layer 60, a color filter layer 70, a upper insulation layer80, a semi-transmitting layer 90, and a green photo-sensing device 100,like the example embodiments of FIG. 4.

The color filter layer 70 includes a blue color filter 70B of a bluepixel and a red color filter 70R of a red pixel, and the greenphoto-sensing device 100 includes a lower electrode 110, a photoactivelayer 130G, and an upper electrode 120. The photoactive layer 130G mayselectively absorb light in a green wavelength region and transmit lightin other wavelength region besides the green wavelength region, that is,light in a blue wavelength region and a red wavelength region, asdescribed above.

However, the green photo-sensing device 100 further includes chargeauxiliary layer 140 and 150 between the lower electrode 110 and thephotoactive layer 130G and between the upper electrode 120 and thephotoactive layer 130G, and further includes a semi-transmitting layer90 between the green photo-sensing device 100 and the color filter layer70, unlike the example embodiments of FIG. 4. The charge auxiliary layer140 and 150 and the semi-transmitting layer 90 are described above.

The image sensor according to example embodiments may improve absorptionefficiency in all wavelength regions of the blue wavelength region, redwavelength region, and green wavelength region, and thus sensitivity ofan image sensor may be improved and performance of an electronic deviceincluding the image sensor may be improved.

The electronic device may be, for example a mobile phone or a digitalcamera, but is not limited thereto.

Hereinafter, the present disclosure is illustrated in more detail withreference to examples. However, these are examples, and the presentdisclosure is not limited thereto.

Manufacture of Image Sensor Example 1

An anode is manufactured by forming a color filter layer including redand blue color filters on a Si CMOS semiconductor substrate, sputteringITO thereon to be about 100 nm thick, and co-depositing a molybdenumoxide (MoO_(x)) and Al thereon to form a 5 nm-thick charge auxiliarylayer. Subsequently, a 70 nm-thick photoactive layer is formed with ap-type semiconductor material (LT-E503, Lumtec) represented byco-depositing the Chemical Formula A and an n-type semiconductormaterial represented by the Chemical Formula B in a thickness ratio of1:1 on the molybdenum oxide and Al thin film (MoO_(x):Al). Subsequently,an 80 nm-thick cathode is formed by chemically depositing ITO on thephotoactive layer, manufacturing a CMOS image sensor.

Example 2

A CMOS image sensor is manufactured according to the same method asExample 1, except for further forming a semi-transmitting layer bystacking a silicon oxide layer having a refractive index of 1.4599 and atitanium oxide layer having a refractive index of 2.4236 in pluralbetween the color filter layer and the ITO anode.

The silicon oxide layer and the titanium oxide layer are alternately andrepeatedly stacked in 8 layers, and each layer has a thickness providedin the following Table 1.

TABLE 1 First layer Silicon oxide layer 200 nm  Titanium oxide layer 163nm  Second layer Silicon oxide layer 37 nm Titanium oxide layer 91 nmThird layer Silicon oxide layer 49 nm Titanium oxide layer 88 nm Fourthlayer Silicon oxide layer 40 nm Titanium oxide layer 85 nm Fifth layerSilicon oxide layer 17 nm Titanium oxide layer 82 nm Sixth layer Siliconoxide layer 88 nm Titanium oxide layer 91 nm Seventh layer Silicon oxidelayer 25 nm Titanium oxide layer 69 nm Eighth layer Silicon oxide layer17 nm Titanium oxide layer 97 nm Total thickness 1239 nm 

Evaluation

Sensitivity and photoelectric conversion efficiency of the image sensorsaccording to Examples 1 and 2 are evaluated.

The sensitivity is evaluated by measuring an electron generation speeddepending on each particular light to obtain a linear graph, while theparticular light is radiated on the image sensors for a predetermined orgiven time, and then calculating the slope of the graph with TsubosakaElectric LSBD-111/4 and Kyoritsu LB-8601.

The photoelectric conversion efficiency is evaluated by using an IPCEmeasurement system (McScience Inc., Korea). First, the photoelectricconversion efficiency is measured in a wavelength range of about 350 nmto 750 nm by calibrating the equipment with using a Si photodiode(Hamamatsu Photonics K. K. Japan), and then mounting the equipment onthe CMOS image sensors according to Examples 1 and 2.

The results are provided in Table 2.

TABLE 2 Photoelectric conversion Sensitivity (mV/lux · s) efficiency (%)Example 1 250 40 Example 2 343 55

Referring to Table 2, the image sensors according to Examples 1 and 2show sensitivity of greater than or equal to about 250 mV/lux·s andphotoelectric conversion efficiency of greater than or equal to 40%, andthus have satisfactory performance, and in particular, thesemi-transmitting layer according to Example 2 shows improvedsensitivity and photoelectric conversion efficiency.

While this disclosure has been described in connection with what ispresently considered to be practical example embodiments, it is to beunderstood that the inventive concepts are not limited to the disclosedembodiments, but, on the contrary, the disclosure is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims.

What is claimed is:
 1. An image sensor, comprising: a semiconductorsubstrate integrated with at least one first photo-sensing deviceconfigured to sense light in a blue wavelength region and at least onesecond photo-sensing device configured to sense light in a redwavelength region; a color filter layer on the semiconductor substrate,the color filter layer including a blue color filter configured toselectively absorb light in the blue wavelength region and a red colorfilter configured to selectively absorb light in the red wavelengthregion; and a third photo-sensing device on the color filter layer, thethird photo-sensing device including, a pair of electrodes facing eachother, a photoactive layer between the pair of electrodes, thephotoactive layer configured to selectively absorb light in a greenwavelength region, and a charge auxiliary layer between the photoactivelayer and one electrode of the pair of electrodes, the charge auxiliarylayer configured to facilitate hole injection or facilitate electroninjection, facilitate hole transport or inhibit hole transport, and/orfacilitate electron transport or inhibit electron transport.
 2. Theimage sensor of claim 1, further comprising: a pair of charge auxiliarylayers between the pair of electrodes, the pair of charge auxiliarylayers on opposite sides of the photoactive layer, each layer of thepair of charge auxiliary layers configured to facilitate hole injectionor facilitate electron injection, facilitate hole transport or inhibithole transport, and/or facilitate electron transport or inhibit electrontransport.
 3. The image sensor of claim 1, wherein the charge auxiliarylayer includes an organic material, an inorganic material, or anorganic/inorganic material.
 4. The image sensor of claim 3, wherein, thecharge auxiliary layer includes the organic material, and the organicmaterial includes an organic compound having hole or electroncharacteristics.
 5. The image sensor of claim 3, wherein, the chargeauxiliary layer includes the inorganic material, and the inorganicmaterial includes a metal oxide material.
 6. The image sensor of claim5, wherein the inorganic material includes at least one metal oxidematerial of molybdenum oxide, tungsten oxide, and nickel oxide.
 7. Theimage sensor of claim 6, wherein the inorganic material includesmolybdenum oxide and aluminum.
 8. The image sensor of claim 1, wherein,the charge auxiliary layer is configured to facilitate hole transport,and the charge auxiliary layer includes at least one material ofpoly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS),polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole,N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (TPD),4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA, and4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA).
 9. The image sensor ofclaim 1, wherein, the charge auxiliary layer is configured to inhibithole transport, and the charge auxiliary layer includes at least onematerial of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA),bathocuproine (BCP), LiF, Alq₃, Gaq₃, Inq₃, Znq₂, Zn(BTZ)₂, and BeBq₂.10. The image sensor of claim 1, wherein, the charge auxiliary layer isconfigured to inhibit electron transport, and the charge auxiliary layerincludes at least one material ofpoly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS),polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole,N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (TPD),4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), and m-MTDATA,4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA).
 11. The image sensorof claim 1, wherein, the charge auxiliary layer is configured tofacilitate electron transport, and the charge auxiliary layer includesat least one material of 1,4,5,8-naphthalene-tetracarboxylic dianhydride(NTCDA), bathocuproine (BCP), LiF, Alq₃, Gaq₃, Inq₃, Znq₂, Zn(BTZ)₂, andBeBq₂.
 12. The image sensor of claim 1, wherein, the blue wavelengthregion has a maximum absorption wavelength (λ_(max)) in a region ofgreater than or equal to about 400 nm and less than about 500 nm, thered wavelength region has a maximum absorption wavelength (λ_(max)) in aregion of greater than about 580 nm and less than or equal to about 700nm, and the green wavelength region has a maximum absorption wavelength(λ_(max)) in a region of about 500 nm to about 580 nm.
 13. The imagesensor of claim 1, wherein the pair of electrodes are light-transmittingelectrodes, and the photoactive layer includes a p-type semiconductormaterial and an n-type semiconductor material, at least one of thep-type semiconductor material and the n-type semiconductor materialconfigured to selectively absorb light in the green wavelength region.14. The image sensor of claim 13, wherein the p-type semiconductormaterial and the n-type semiconductor material form a pn junction. 15.The image sensor of claim 14, wherein the light-transmitting electrodesinclude one of a transparent conductor layer, a metal layer, and a metallayer doped with a metal oxide, the p-type semiconductor materialincludes one of quinacridone and a derivative thereof, and the n-typesemiconductor material includes a cyanovinyl group-containing thiophenederivative.
 16. The image sensor of claim 1, further comprising: afocusing lens on the third photo-sensing device.
 17. The image sensor ofclaim 1, further comprising: a metal wire beneath the at least one firstphoto-sensing device and the at least one second photo-sensing device.18. The image sensor of claim 17, wherein the metal wire includes one ofaluminum (Al), copper (Cu), silver (Ag), and alloys thereof.
 19. Anelectronic device comprising the image sensor of claim
 1. 20. Theelectronic device of claim 19, wherein the electronic device is one of amobile phone and a digital camera.
 21. The image sensor of claim 1,wherein the semiconductor substrate further comprises a charge storagedevice.